My non-exhaustive 5-10 mins of googling has determined that these vehicles are BM-11 Multiple Rocket Launchers. Showcased on the Day of the Sun (태양절) for the Eternal President of North Korea, Kim Il-sung's 100th birthday in a grand military parade. An official holiday since 1968, the birthday was renamed to Day of the Sun in 1997. His first name, Il-sung is Korean for "become the sun".
The BM-11 is a derivative of the Soviet BM-21 "Grad". I feel like I've heard the Russian word "grad" only in the context of military but never knew what it meant. Well, the "Grad" nickname for this vehicle means "hail", as in the hail of rockets that will rain down upon you as all 30 rockets across its two banks can be fired in as little as 15 seconds.
Previously I've posted a photo of a BM-24 multiple rocket launcher, but little did I know that the BM stands for boyevaya mashina, which is Russian for combat vehicle. I'm not quite sure what the "11" designator is in reference to, but I would guess the specific type of rocket that fires out of the launch tubes.
The range of these 122mm rockets is probably on the order of 20km (12mi), but may be further. Information on North Korean combat vehicles while perhaps available, is not the as easily as accessible despite the fact that these aren't exactly new vehicles or systems.